Yes, it's in the wallet file protected only by your password, if there's no password set, it's in plain text that can even be read by a text editor.
Even if you changed that password or set a password in one copy of the wallet file, the other copies wont be affected by that password change.

That's because the wallet file, password or seed phrase aren't saved in a server but the local machine where the wallet is saved.

This year's "April Fools" event wasn't as crazy as the previous IMO.

For reference, here's the admin's reply to the "capcha update" thread: Re: New CAPTCHA now required before posting
Here's the list of previous April Fools threads: [Compilation] All pranks that was made by theymos in every April Fools Day come.

The proper way to do this is to unload the wallet first in "File->Close wallet" menu while the target wallet is selected or unloadwallet command.
You can now proceed to rename the wallet in the 'wallets' folder, then load it again in Bitcoin Core.

If you have pruned your blockchain, doing this may trigger another full IBD as indicated in the pop-up message.

You can use a 'watching-only' 'blank' 'descriptor' Bitcoin Core wallet to do this.
You'll just have to import all of those mnemonic seed's derived extended public keys as descriptors.

To do that, follow this guide learn how to create descriptors from the extended public keys and import each descriptor to Bitcoin Core.
Link: http://bitcointalk.org/index.php?topic=5399337.msg60178631#msg60178631

The guide is specific to import Electrum master public key(s) (account extended public key) to Bitcoin Core.
If you can't find a way to export each mnemonic seed's extended public key, import them to an offline Electrum (link) first to get each's master public key, one at a time.
Or use iancoleman's BIP39 tool (link), select the correct derivation path and get the "Account Extended Public Key" to be compatible with the guide.

The good thing with this is, you can import as much descriptors your hardware can handle compared to online APIs or SPV wallets with a quite low limit.
The limitation is obviously, it's Bitcoin-only and will require a lot of internet bandwidth and storage space. (pruning isn't recommended for your use-case)

I was going to suggest to clear the App's cache and saw that there's someone already suggested it to the web version,
but based from your reply, you didn't in the App?

To do that, go to your Phone's setting, look for "Apps", "Manage Apps" or similar name (where your installed apps are listed).
Find and click "Blockchain" app and tap to open "Storage", tap "Clear Cache" to clear its cached data, force closing it may be needed or at least restart the phone.
Be sure not to click "Clear Storage" or it will reset to its newly installed state.

The "3 days behind" message doesn't mean that it'll take 3 days to sync, it's just 3 days worth of blocks which usually sync within an hour in my machine.
I suspect that there's something wrong with your node.

Close everything, restart the PC (to make sure everything isn't running in the background) and then start Bitcoin Core to see if it'll continue from where it left.
Take note that Bitcoin Core's GUI might freeze while it's syncing but it's still active in the background,
closing it forcefully might corrupt your "txindex", "chain_index" or "blockchain".
If it's not frozen, you can close it safely.

After it fully sync, the close it and open Armory, let it manage Bitcoin Core (it'll launch bitcoind in the background).
If there's an issue, check you debug.log file for errors in Bitcoin Core's data directory to see why it's not progressing.

Yeah, blockexplorers don't actually have 100% identical data, they mostly rely on their own copy of each coins' blockchains.

As for still showing invalid transaction, it's their unique "feature" to keep those data that aren't in their mempool or blockchain.
It's actually useful in cases like this.

So the transaction wasn't replaced by another with a different output and just had a replaced parent (rbf to bump the fee) or dropped from mempools..
Glad to see that it went well.

I was talking about the timeframe when the said transaction was gone missing.
Even with the ordinals bloating the blockchain, there are still a lot of time when the mempools do not reach the default maximum size, like right now or yesterday.

He did spent puzzles 161-256 just like what others have suggested since those are absurdly impossible to bruteforce.
That's about 3 months after the post.

The author of this thread Bulista (Link to OP) "discovered" it and though it's a puzzle, that's why this is dubbed as a "puzzle" despite having no pattern to solve.
Bitcoin transactions aren't anonymous, everything can be seen if you have a copy of the blockchain or at least have the ability to access resources online.

Okay, there a few pointers:

• if the transaction's input was spent in another transaction with a different output, then it's certainly intentional.
• if the transaction's parent transaction was replaced which invalidated your (child) transaction, there's a chance that it's intentional or not.
  It depends if the sender just bumped the fee through rbf which unintentionally invalidated all of its child transactions.
  
• if it's for having a very low fee rate, it may not be intentional but with today's average mempools size, even 1sat/vB shouldn't be evicted from most mempools.

Note: These are only possible with unconfirmed transactions.

I have zero info about the deal so I can't comment on that.
But please remember my note above about waiting for a confirmation before finalizing a deal.

The transaction was turned into a "local transaction" because the server that you're using can't find it in its mempool.
And since you can't also find it in any blockexplorer, chances that it's dropped, replaced or has a replaced parent is high.
Of course, providing the Transaction ID may help us determine if it's possibly intentional or not.

The only course of action here is to inform the sender that his transaction was dropped so that he can send you another one.

Additionally, if you're in a deal, waiting for at least 1 confirmation (more if valuable) is a must before finalizing the deal.

To be fair, the puzzle creator did said that it's from a deterministic wallet: http://bitcointalk.org/index.php?topic=1306983.msg18765941#msg18765941
But I think zahid is not on the right track since from what I understand, the consecutive keys are "masked" with zeros, as in zeros replaced the starting bits of the private keys.

---

For example: if the three consecutive keys from my wallet are:

• 6b86b273ff34fce19d6b804eff5a3f5747ada4eaa22f1d49c01e52ddb7875b4b
  
• d4735e3a265e16eee03f59718b9b5d03019c07d8b6c51f90da3a666eec13ab35
  
• 4e07408562bedb8b60ce05c1decfe3ad16b72230967de01f640b7e4729b49fce

When masked with zeros (HEX for example, creator used bits), those will be:

• 000000000000000000000000000000000000000000000000000000000000000b
• 0000000000000000000000000000000000000000000000000000000000000035
• 0000000000000000000000000000000000000000000000000000000000000fce

---

So by going for the initial entropy, hdseed, mnemonic seed or master private key of the source of the puzzle's keys,
it'll be impossible since he will be looking for collision with the entire range of the 'undisclosed HD source' instead of the limited range of each keys.

Since you didn't mentioned the option that I gave you,
I suppose removing the wallet's password while offline to manually get the keys from the wallet didn't worked because it crashed regardless of the offline status?

Have you tried increasing the machine's "paging file" to a very large amount (restart it) and see if it'll stabilize?

There's a certain chance that it'll be pre-selected.
Since it's in the data directory where the configuration file is included where the previously loaded wallet directories are listed,
chances that it'll be the first wallet that a newly installed Electrum will show during its "Install Wizard" screen,
you wont even have to setup the wallet since its already there, it'll just open. You can add the password in the wallet menu if it's not encrypted. (sounds familiar?)

Plus the data directory isn't deleted if the previous owner deleted/uninstalled Electrum.

Why? Is there a chance that the PC was someone else's?
Because that's a good start since you can ask him if he used Electrum before and the whereabouts of that address.

It's online because you left Bitcoin Core running and Armory found it.
The balance is zero because Armory hasn't done preparing its database yet since Bitcoin Core isn't synced.
All you need to do is to wait for it to fully sync in order for your transaction to appear.

If both Armory and Bitcoin Core are configured with default data directories and you have enough free space in that dir (about 600GB+ total),
simply running Armory and let it manage Bitcoin Core should be sufficient to fully sync the wallet within the estimated time you saw in Bitcoin Core.

If you do not want to download and store all that data, follow to the link provided by Bitmaxz above.

So those wallets are just created recently and not before creating your Electrum wallet?
If so, the address can't be from any of those.
If not and those are before Electrum: it's worth to check those wallet's address list if it belongs there.

For the additional info requested by blockchain.com (not affiliated with Bitcoin), it's mandatory to their Buy/Sell and Exchange services.

Then the wallet is created by someone else or as mentioned above, already there when you installed Electrum.
It's possible since Electrum's data directory is separate from the install directory and wont be deleted during uninstall.

There also inconsistencies that leads to my suspicion that you've totally misremembered what happened.

The old version is still recoverable using their backup phrase which isn't BIP39 seed phrase but only a way to access the user's login credentials which is the "Wallet ID" and "Password".
And during that time, users are given a encrypted json copy of their wallet file in their Email which can be used to recover their Bitcoins.

The major issue is with the very first version which only has the "Alias" that can't be used to login today.
But IIRC, I've seen some successful recovery of such wallet through their slow customer support by providing the required info.

To see if there are successful attempts of recovery of old blockchain(.)info wallets, browse through this board: Service Discussion > Web Wallets

Have you installed Bitcoin Core in a different directory as well as its data directory?

Because it seems like a pathing issue and bitcoind can't be launched either.
Refer to this guide to setup the correct path to your Bitcoin data/install directory: https://btcarmory.com/docs/pathing

Alternatively, you can set it all in the GUI in "File->Settings":
"Bitcoin Install Dir" should point to the directory where Bitcoin Core is installed.
"Bitcoin Home Dir" should point to your bitcoin data directory.

For starters, just follow the instructions in the reference client's GitHub repository: https://github.com/bitcoin/bitcoin/blob/master/doc/tor.md

Since there's limited info, I'll just ask if you've setup a custom data directory?
Because is you did and set it up via the GUI's "Welcome Screen" or as a command line option, the bitcoin.conf file should be in that directory instead.

If not, it must be something else.

Does this "Install Window" seem familiar?:

Because that's where you've entered that "1N8vh" address that you may have copied from somewhere else.
I'm thinking that you may have it in your clipboard back then, pasted it there, then proceeded to create the wallet.

Have you been using other wallet(s) aside from Electrum before?

That's the rate for Coinbase's "Commerce" service/app which isn't the wallet.
For the custodial wallet's "Network fee", refer to this link instead: help.coinbase.com/en/coinbase/trading-and-funding/pricing-and-fees
Expand "Primary balance" and read the part with "For transactions on cryptocurrency networks".